The purpose of this study was to analyze the presence of different yeasts in the facilities of four wineries from the D.O.Ca. Rioja region in Spain. The study was conducted through the identification of the yeasts via the PCR-RFLP technique of the ITS region of rDNA. The diversity of non-Saccharomyces yeasts found in wineries has previously only been studied to a limited extent, despite the fact that these yeasts take part both in the start of spontaneous fermentation and in the changes which occur in the wines during their subsequent conservation. Most earlier studies carried out on cellar ecosystems have focussed on the clonal diversity of Saccharomyces cerevisiae. The results obtained in this study indicated that the presence of non-Saccharomyces yeasts in facilities is higher than that of the S. cerevisiae, with percentages of over 60% in all the wineries analyzed. Yeasts belonging to 10 genera and 18 species were isolated, but the only genera present in all four wineries were Cryptococcus, Pichia, and Saccharomyces. The Zygosaccharomyces bailii yeast responsible for taint was detected in one cleaned winery, in both the winemaking equipment and the fermenting must. It was also noted that the quantity and type of yeasts present in the facilities are related to the product used for cleaning them. It is also necessary to point out that the cleaning of the cellars prior to the reception of the grapes does not completely eliminate the yeasts present, so that these can subsequently become part of the vinification process. (We recommend that you consult the full text of this article).